In recent years, there have been requests for further miniaturization of solid-state image sensors composed of CCD (charge-coupled devices) or CMOS (complementary metal oxide semiconductor) sensors, used in digital cameras and mobile telephones.
In order to meet such requests to miniaturize solid-state image sensors, there are proposed solid-state image sensors and manufacturing methods thereof, in which the solid-state image sensors are manufactured by attaching a transparent protection member to an imaging device wafer, on which many light-receiving parts of imaging devices have been formed, through spacers formed in positions separately surrounding the light-receiving parts, and thereafter separating the joined substrate into individual solid-state image sensors (see Japanese Patent Application Laid-Open No. 2001-351997, for example).
An example of the above-mentioned solid-state image sensor is described with reference to FIGS. 1 and 2, which are a perspective view illustrating an external configuration of a solid-state image sensor 1 and a cross-sectional view thereof. The solid-state image sensor 1 is constituted of: an imaging device chip 2 manufactured by cutting an imaging device wafer on which imaging devices 3 have been formed; a frame-shaped spacer 5 attached on the imaging device chip 2 and surrounding the imaging devices 3; and an optically-transplant protection member 4 attached to the spacer 5 to seal the imaging devices 3.
As shown in FIG. 2, the imaging device chip 2 includes: a rectangular chip substrate 2A; the imaging devices 3 formed on the chip substrate 2A; and pads or electrodes 6, which are arranged around the imaging devices 3 and to be wired with the external. The chip substrate 2A is made of monocrystalline silicon, for example, and has the thickness of about 300 μm, for example.
The protection member 4 is made of optically-transplant material such as resin and glass of heat-resistant and chemical-resistant, for example, and has the thickness of about 500 μm, for example.
It is preferable that the spacer 5 is made of material having the properties, such as the thermal expansion coefficient, similar to those of the chip substrate 2A and the protection member 4, and the spacer 5 is made of polycrystalline silicon, for example. A part of the frame-shaped spacer 5 has a cross-section about 200 μm in width and about 100 μm in thickness, for example. An end face 5A of the spacer 5 is joined to the chip substrate 2A with an adhesive 7, and the other end face of the spacer 5 is joined to the protection member 4 with an adhesive 8.